21÷7=3 what is the meaning of the unknown factor and quotient?

40 points plato monica built a remote-controlled, toy airplane for a science project. to test the plane, she launched it from the top of a building the plane traveled a horizontal distance of 50 feet before landing on the ground. a quadratic function which models the height of the plane, in feel, relative to the grouna, at a horizontal distance of x feet from the butiding is shown. since the domain the airplane while it was in the air, the value of the domain should be restricted to the space 1 a.the maximum height of b.the horizontal distance covered by c.all the heights in the trajectory of space 2 a.-10 b.125 c.negative infinity d.0 space 3 a.infinity b.50 c.125 d.225